(a) Technical Field
The present invention relates to a three-way valve integrated with a radiator for a vehicle. More particularly, it relates to a three-way valve that is integrally formed with an outlet of a radiator for use in a fuel cell vehicle that advantageously improves thermal management of a fuel cell stack.
(b) Background Art
In general, a fuel cell stack for a vehicle provides an optimal output when coolant that is maintained at an optimal temperature is supplied to the inside of the fuel cell stack.
Accordingly, it is very important to ensure a stable output of the fuel cell stack by properly controlling the temperature of the coolant that is fed into the fuel cell stack. To this end, a thermal management system (TMS) is typically employed in a fuel cell vehicle as a means for maintaining the temperature of the fuel cell stack.
A convention thermal management system for regulating the temperature of a fuel cell stack is shown in FIG. 1. Generally, a conventional TMS includes a fuel cell stack 100, a pump 110, a radiator 120, a heater 130, a bypass loop 140 extending from pump 110, and a radiator loop 150 extending from the radiator 120, which constitute a coolant circulation loop.
In the conventional TMS, the flow of the coolant in each loop is controlled by an electronic three-way valve 160.
In particular, the bypass loop 140 is generally employed to provide smooth operating conditions by rapidly increasing the system operating temperature during initial start-up.
On the other hand, when the system becomes overheated or exceeds a predetermined operating temperature established in the three-way valve 160, the three-way valve 160 opens the radiator loop 150 to supply cold water. The cold water supply, in turn, reduces the coolant temperature.
That is, the three-way valve 160 in a conventional TMS is generally used to mix the hot water of the bypass loop 140 and the cold water of the radiator loop 150 to maintain a specific temperature at which the fuel cell stack provides an optimal output efficiency.
For example, during initial system start-up, the coolant temperature is typically low because the amount heat produced by the fuel cell stack is low. Under these conditions, the coolant typically flows along a circulation line connected between the pump 110, the three-way valve 160, the heater 130, and the fuel cell stack 100. This circulation path occurs because it is not generally necessary under initial start-up conditions to send the coolant to the radiator as the coolant temperature is already low.
However, when a predetermined period of time elapses after the initial start-up conditions, the amount of heat generated by the fuel cell stack becomes increased. Accordingly, as the temperature of the coolant flowing through the bypass loop 140 is rapidly increased, the three-way valve shuts off the bypass loop 140 and opens the radiator loop 150 in an appropriate manner such that the coolant flows along a circulation line connected between the fuel cell stack 100, the pump 110, the radiator 120, the radiator loop 150, the three-way valve 160, and the heater 130.
Generally in operation, the three-way valve 160 receives a signal indicating the temperature of an inlet of the fuel cell stack 100 and appropriately controls the degree of opening of both loops (i.e., the bypass loop 140 and the radiator loop 150) in order to supply the coolant at a constant temperature to the fuel cell stack, regardless of the external environment.
However, the conventional TMS described above is disadvantageous because of the requirement of both the bypass loop and radiator loop.
That is, the conventional TMS cooling systems known in the art for regulating the temperature of the fuel cell stack of a fuel cell vehicle require both the bypass loop and the radiator loop to achieve the proper balance between rapidly heating the system during initial start-up and cooling the system when overheated. The requirement of both loops in this manner by the conventional TMS known in the art result in variety of disadvantages, including, higher manufacturing costs, increased vehicular weight, and restrictions as to the freedom of system design. These disadvantages result in an overall reduction in the efficiency of known TMS. An improved system that overcomes these disadvantages would be a welcome advancement in the art.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention. Therefore the above may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.